Re: 3.6 Inheritance Documentation
От | Peter Eisentraut |
---|---|
Тема | Re: 3.6 Inheritance Documentation |
Дата | |
Msg-id | de8e9b34-0e9d-9fee-c9c5-bb2238c77c2a@eisentraut.org обсуждение исходный текст |
Ответ на | 3.6 Inheritance Documentation (PG Doc comments form <noreply@postgresql.org>) |
Список | pgsql-docs |
On 02.08.23 21:54, PG Doc comments form wrote: > In the provided example, the cities table and the capitals table have a > parent-child relationship through inheritance. However, querying the cities > table directly (e.g., SELECT name, elevation FROM cities WHERE elevation > > 500;) will not automatically include data from the child table, capitals. > Inheritance in PostgreSQL does not implicitly combine data from parent and > child tables in a single query. This observation is patently incorrect: CREATE TABLE cities ( name text, population real, elevation int -- (in ft) ); CREATE TABLE capitals ( state char(2) UNIQUE NOT NULL ) INHERITS (cities); INSERT INTO cities (name) VALUES ('Ithaca'); INSERT INTO capitals (name, state) VALUES ('Albany', 'NY'); SELECT * FROM cities; name | population | elevation --------+------------+----------- Ithaca | | Albany | | (2 rows) SELECT * FROM capitals; name | population | elevation | state --------+------------+-----------+------- Albany | | | NY (1 row)
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